The method and apparatus of the present invention relate generally to determining the dimensions of an object. More particularly, the apparatus and method of the present invention relate to determining the dimensions of an object using a target having a known dimension and a scanning light beam.
A major concern in the freight shipment industry is the individual size of packages and how packages are integrated into a specific carrier container used in shipping. Specifically, packages are shipped by many different modes of transportation including tractor-trailers, air planes, ships, etc. Each of these forms of carrier transportation have capacity limits per shipment and may have different sized carrier containers. As the cost of shipping continues to rise, it becomes more important for freight carriers to evaluate the size of individual packages to determine how to best maximize shipment space in their individual carrier containers used for shipment of the packages.
For example, many manufacturing companies that produce a line of products attempt to standardize their packages and ship packages in bulk form such that capacity of the specific carrier container utilized can be maximized. Further, the cost for shipment can be more easily determined and minimized. Problems occur, however, when the freight carrier is involved with several different customers all of which have different sized packages that are to be integrated into one carrier container for shipment. In these instances, it is much more difficult to maximize utilization of the carrier container""s capacity and keep shipping cost to a minimum. For this reason, systems have been designed that allow a freight carrier to determine the size of individual packages such that shipping decisions, as far as cost and capacity are concerned, can be made.
These conventional package measurement systems vary widely in design and implementation. For instance, some conventional systems are implemented in conveyor belt systems and take measurements of the dimensions of packages using infrared transmitters and sensors that are positioned on the conveyor belt and sense when a package is present. Based on the time it takes for the package to pass the infrared sensor and the speed of the conveyor belt, the system can determine the dimensions of the package. Other systems implement measurement boxes having known dimensions in which each individual package is placed. These measurement systems use light curtains, infrared transmitters and sensors, or sonic transmitters and transducers that sense the amount of the measurement box the package occupies to determine the dimensions of the package. Still further, other systems use a measurement box that has scales in an X, Y, and Z axis that are bar coded. The package to be measured is placed in the measurement box and bar code scanners read the bar codes associated with the portions of the scales that are visible at the edges of the box to determine the package""s dimensions.
Although the above package measurement systems provide devices and methods for the determining the dimensions of a package, they do have some drawbacks. Specifically, many of these conventional measurement systems are mostly stationary and are not conducive to portability. They typically employ the use of conveyor belts, multiple sensors, or measurement boxes that are not easily transportable. These measurement systems can also be costly and may require an unacceptable amount of space for implementation. Portability of the measurement device, cost for implementation, and overall size of the measurement system, however, are important factors to be considered in the use of a package measurement device by a freight carrier.
Specifically, some freight carriers are engaged in the shipment of packages from private individuals and a large number of different companies on a non-bulk shipment basis. In many instances, the number of packages to be shipped per customer on any given day is typically a small quantity, and the carrier typically sends personnel to the customer""s facility for pickup of packages or the customer will bring the packages to a regional office for shipment. Because the packages are typically not part of a bulk shipment, the individual packages may vary widely in size, and the freight carrier is usually not aware of the dimensions of any of the packages prior to pickup.
As discussed above, however, the overall size of the package may affect the cost of shipment. This creates a problem in that the cost of shipment of the package is usually negotiated at the time of pickup, not after the package has been later processed for shipment. Due to these factors, it is advantageous to measure the package at the pickup site such that the cost associated with the package size can be added to the customer""s bill. Additionally, it is advantageous to electronically store the dimensions of the package such that this information can be subsequently used to determine logistics for integrating the package with other packages into a carrier container for shipment.
Conventional systems, however, are typically not conducive to point of purchase measurement of the package such that the customer can be immediately charged for the size of the package to be shipped and the dimensions can be electronically stored. Specifically, in instances where the freight carrier picks up the package at the customer""s facility, conventional measurement systems do not provide the portability needed to allow the freight carrier to quickly determine at the pick up point the dimensions of a package. Likewise, when packages are brought to a regional office by the customer, conventional measurement systems do not provide cheap, cost effective, and size manageable measurement devices. Although conventional conveyor belt or measurement box systems might be used in these instances, the cost and space needed to accommodate conventional conveyor belt measurement systems and the cost of sensors and materials needed for conventional measurement box systems can significantly increase shipping cost.
Because portability, space, and cost are a major concern, a portable measurement system is needed that allows the freight carrier to easily determine the dimensions of a package at point of pick up such that the cost associated with shipping of the package can be easily assessed to the customer and the package dimensions can be stored electronically such that the dimensions are readily accessible for later shipment decisions.
As set forth below, the method and apparatus of the present invention for measuring the dimensions of an object can overcome many of the deficiencies identified with conventional package dimension measurement systems. In particular, the method and apparatus of the present invention provides a portable measurement system that allows the user to quickly and easily take the measurements of a package. The method and apparatus of the present invention stores the dimensions of the package such that these dimensions may be used to determine the cost for shipping the package and also the space needed for integrating the package with other packages in a carrier container for shipment. In particular, the present invention provides a portable measurement system that requires a minimum number of components, is cost effective, and is miniaturized compared to many conventional measurement systems.
These and other advantages are provided, according to the present invention, by an apparatus for measuring at least one dimension of an object as represented by the distance between two points of interest associated with the object. The apparatus includes a transmitter that is positioned at a first point of interest on the object. The transmitter transmits a scanning light beam rotated at a predetermined angular velocity. Located at the second point of interest on the object is a target. At least a portion of the target defines a first plane that reflects the scanning light beam as the scamming light beam traverses across the target. To receive the reflected signal from the target, the apparatus of the present invention further includes a receiver positioned at the first point of interest. Additionally, the apparatus of the present invention includes a processor for processing the reflected signal and determining the dimensions of the object.
In operation, the transmitter transmits a scanning light beam rotated at a predetermined angular velocity. As the scanning light beam rotates, the light beam traverses across the target located at the second point of interest and the first plane of the target partially reflects the light beam back to the receiver. The receiver receives the reflected signal, and the processor determines the dimensions of the object by calculating the distance between the two points of interest.
In one embodiment of the present invention, the apparatus determines the dimension of the package based on a known width of the target, the angular velocity at which the transmitter rotates the scanning light beam, and the time required for the scanning light beam to traverse the known width of the target. Specifically, as the transmitter transmits the rotating scanning light beam, the rotation of the scanning light beam creates an arc of rotation, a portion of which traverses the known width of the target. In this embodiment, the radius of the arc of rotation of the scanning light beam defines the distance between the transmitter and the target. To determine the radius of the rotational arc (i.e., the distance between the transmitter and the target which is the dimension of the package), the apparatus further includes a counter connected to the receiver.
In operation, the transmitter transmits a scanning light beam rotated at a predetermined angular velocity. The scanning light beam traverses across the target and the first plane of the target reflects the scanning light beam. As the reflected signal is received by the receiver, the counter accumulates the time required for the scanning light beam to traverse the known width of the first plane of the target. Using the known width of the target, the angular velocity of the scanning light beam, and the time required for the scanning light beam to traverse the target, the processor determines the radius of the arc of rotation which corresponds to the dimension of the object.
As discussed above, the apparatus of the present invention includes a target having a first plane that at least partially reflects the scanning light beam. In some embodiments of the present invention, the first plane of the target includes at least two reflective transition points that are spaced apart at a known distance. In this embodiment, the scanning light beam traverses across the reflective transition points, and the receiver receives signals indicating when the scanning light beam traverses the reflective transition points. These received signals are used by the processor to determine the dimensions of the object.
Depending on the embodiment, the reflective transition points of the target of the present embodiment may take several forms. Specifically, in one embodiment of the present invention, the target includes a nonreflective portion surrounded by a reflective portion where the edges of the nonreflective portion defines the transition points (i.e., a black strip of known width superimposed on a white target). In another embodiment, the target includes a plurality of nonreflective portions spaced apart from each other by reflective portions having known widths.
In addition to providing an apparatus and method for determining the dimensions of an object, the present invention also provides an apparatus and method for first aligning the transmitter and the target prior to determining the dimension of the object. In some embodiments, it advantageous to align the center of the target with the center of the transmitter such that the scanning light beam properly scans the target. Specifically, in these embodiments, the transmitter rotates the light beam through a rotational arc. In order to obtain proper alignment between the target and the transmitter, it is advantageous to align the midpoint of the first plane of the target to the midpoint of the rotational arc of the scanning light beam.
To align the target and the transmitter, in one embodiment of the present invention, the transmitter includes an alignment mode. In the alignment mode, the transmitter initially provides a stationary light beam that intersects the midpoint of the rotational arc of the scanning light beam. Using this stationary light beam, the user can align the midpoint of the first plane of the target to the stationary light beam to thereby align the target and the transmitter. In some embodiments, of the present invention, the transmitter initially transmits the stationary light beam allowing the user to align the target to the transmitter, and after a predetermined period of time, begins to rotate the scanning light beam such that the dimensional measurement can be made.
The present invention also provides a method and apparatus for calibrating the measurement system. Specifically, as discussed above, the apparatus of the present invention includes several components used in operation to determine the dimensions of the object. As these components are subject to manufacturing tolerances, age drift, and temperature drift, there may be variations in the performance of the apparatus. Additionally, there may be measurement errors associated with differences between the plane of the target and the rotational arc of the scanning light beam. As such, in some embodiments, it may be advantageous to account for some of these errors.
To calibrate the measurement system, in one embodiment of the present invention, a target of known width is placed at a second point of interest that is a known distance from a first point of interest where the transmitter is located. The transmitter, in a calibration mode, scans the target with the scanning light beam at a plurality of different distances between the transmitter and the target. For each of the distances, the processor stores the distance and associated time for the scanning light beam to traverse the target in a table. In operation, after the apparatus has measured the time required for the scanning light bean to traverse the target, the processor accesses the table and using the measured time interpolates between the stored values (if it does not match one of the stored values) to determine the dimension of the object.
As mentioned above, the angular velocity at which the transmitter rotates the scanning light beam may be affected by changes in operating temperature. As such, either alternatively or in addition to the above calibration mode, the present invention also provides an apparatus and method for calibrating the measurement system to compensate for the effects of temperature on the performance of the measurement system. In this embodiment of the present invention, the apparatus further includes a temperature sensor connected to the processor. Additionally, the apparatus of the present invention also includes a memory device containing a stored table of temperature calibration data. In this embodiment of the present invention the apparatus in a calibration mode, is subjected to several different temperatures and calibrated at known distances. This calibration data for each temperature is stored. In operation, the sensor senses the operating temperature of the measurement system and supplies this information to the processor. The processor receives the operating temperature and accesses the calibration table in the memory device. The processor locates the correct calibration data associated with the sensed temperature and may either compensate the dimension measurement of the object with the calibration data or use the stored values to provide a temperature compensated measurement.
In addition to calibrating the measurement system to account for changes in the angular velocity of the scanning light beam, in some embodiments it is also advantageous to ensure that the transmitter has reached steady state operation prior to performing the dimension measurement. Specifically, when the measurement system is initially actuated, there may be some delay time prior to the transmitter transmitting the scanning light beam at predetermined angular velocity. To determine whether the transmitter has reached steady state, in one embodiment of the present invention, while the transmitter is transmitting the scanning light beam, the processor repeatedly samples the light beam reflected by the target and calculates the distance between the two points of interest. The processor further repeatedly compares the calculated distances to each other. When the calculated distances for each sample of the reflected light beam produces dimensional values that are relatively equal, the processor determines that the transmitter is in steady state operation. In an alternative embodiment, the processor eliminates from consideration an initial preset number of scans before performing the measurement.
As mentioned above, the transmitter and the receiver are located at the first point of interest on the object. In some embodiments, it is advantageous to incorporate the transmitter and receiver into a housing for portability and to protect the components from weather. Thus, in one embodiment of the present invention, the apparatus further includes a housing that has securing means for housing the transmitter and receiver. This housing provides a durable container to shield the transmitter, receiver, and other components from environmental elements and also to provide a portable, ergonomic package.
In embodiments where the transmitter and receiver are located in a housing, it may be advantageous to provide a reference point that will engage the first point of interest of the object and align the transmitter and receiver to the object. As such in one embodiment of the present invention, the housing further includes a reference point that engages with the first point of interest of the object to be measured. The reference point allows the measurement system to be placed consistently and reliably at the first point of interest of the object such that accurate measurements can be acquired. Additionally, the reference point may include an alignment means that maintains the scanning light beam perpendicular to the plane of the target.
In some embodiments of the present invention, the reference point may be placed in a location such that the transmitter and the first point of interest of the object are separated by an offset distance. In this embodiment, the offset distance between the reference point and the transmitter must be accounted for in the determination of the dimension of the object. Specifically, because the transmitter may be either closer or further away from the target than the first point of interest is to the target. In this instance, it is advantageous for the processor to compensate for the dimensional measurement for this offset distance. As such, in one embodiment of the present invention, the processor determines the distance between the first and second points of interest based on the light beam reflected from the target and either subtracts or adds the horizontal difference between the transmitter and the reference point on the housing to the dimension measurement.